The use of electric power generated by wind has drastically increased in recent years. To improve economy by increasing the capacity of a single machine, there has been an increasing demand for permanent magnet rotating electric machines with a large capacity of 1 MW or more. When a large-capacity permanent magnet rotating electric machine is used, even if its efficiency is high, large loss is generated as an absolute value. To enable a large-capacity permanent magnet rotating electric machine to have a generated heat density equal to that of a small-capacity permanent magnet rotating electric machine, the body of the large-capacity permanent magnet rotating electric machine must be enlarged. When the body of the rotating electric machine is enlarged, however, its weight is increased and thereby manufacturing costs and construction costs are increased. Accordingly, it is necessary to increase the output density with a small body.
However, an increase in output density causes an increase in generated heat density, so high cooling performance is required. As a result, an increase in cost is brought. If a permanent magnet rotating electric machine has a structure that does not easily generate heat, merits (a reduced body and high efficiency) gained by the use of permanent magnets are lessened, impairing electric characteristics. Then, it becomes difficult to satisfy specifications for electric power generators. To achieve highly efficient cooling at a low cost without impairing electric characteristics, a structure suitable for cooling is a requisite.
Patent Documents 1 and 2 disclose cooling structures of rotating machines of this type that achieve highly efficient cooling at a low cost without impairing electric characteristics.
That is, Patent Document 1 discloses a structure in which a stator iron core has fins shaped like a star, in each of which a coolant flow path for cooling is formed. Patent Document 2 discloses a structure in which a heat-collecting jacket, in which a coolant flows around the outer circumference of a stator, is provided; and a heat dissipating jacket and a ventilation path are disposed outside the heat-collecting jacket.